Preserving the properties in the drying process while producing the nano particle and/or colloidal particle is a challenging task. It is imperative that the surface area, size, shape, humidity, oxidation state etc., of the nanomaterial is maintained at the highest level after the processing.
As for the other nanomaterials, which have a high sensitivity (such as iron and other oxygen sensitive metals) for the surrounding environment, such as oxygen, temperature, etc., an improper processing may have changing effects on the properties such as surface, shape, complexity, assembly, size etc., and they may be transformed into other undesirable manufactured material. For example, a metal nanoparticle to be manufactured in a specific oxidization state such as zero valent iron nanoparticles Fe(0) if the drying conditions are not controlled, they turn into other forms such as Fe2O3, FeOOH or Fe3O4.
Another example that highlights the extent of the problem is during manufacturing process various nanomaterials are damaged as Nano-sol gel. In fact, they might be completely lost during the drying process.
Many industrial solutions have been used to solve this problem. However, some of which are complex, costly when operating, and do not meet the purpose of preserving the material in the desired oxidation state. Air-drying, span-drying and freezing-drying are not effective methods to dry the nanomaterials which have a high sensitivity of the surrounding environment. Indeed, changing the temperature during the drying process by raising the temperature (or reducing it) leads to changing the properties of the manufactured material, and not produced it as required. Moreover, air-drying is the least efficient method in drying, despite the low cost when operating, because it does not include the process of raising or reducing the temperature.
Therefore, there exists a need for an improved method and apparatus to generate nano material without the use of cumbersome process and involvement of a highly skilled technician.